This application pertains to the art of fabrication of specialized seating, and more particularly to computer aided and numerically controlled seat design and fabrication.
The invention is particularly applicable to fabrication of prescription wheelchair seating and will be described with particular reference thereto. It will be appreciated, however, that the invention has broader applications such as in fabrication of beds, seating units, foot support, or the like.
It is estimated that more than 45 million people in the United States are affected by disabilities which impair their mobility. One common method used to overcome such disabilities is use of wheelchairs. The number of daily wheelchair users exceeds 0.75 million people.
Disabled individuals often spend considerable time a wheelchair. Accordingly, and interface between the individual and the wheelchair is crucial. Without an accurate fit of the support system, pressure sores and postural deformity may result. Expenses for treatment of pressure sores and deformities are extremely high, and are increasing. Estimates of the costs associated with the healing of pressures sores in 1978 were given to be between $10,000 and $46,000. More recently, the range is shown to have widened to be from $3,400 to $86,000 with an increase of the mean costs of nearly $10,000.
When chosen correctly, cushions and body supports can be effective in reducing the risk of pressure sores and for maintaining postural alignment. The subject of wheelchair cushion prescription is well documented in the literature. Various methods of selection, testing, and determination of specialized characteristics, have been described. Even when acceptable, individualized, seating dimensions have been decided upon, fabrication of a wheelchair bearing the appropriate seating dimensions must be accomplished.
Presently, typical fitting and fabrication for prescription wheelchair seating is accomplished by what is referred to as the "dilatency casting method," which is described as follows. A patient is seated on a wheelchair form which generally includes a horizontal portion pivotally connected to a vertical portion. Various orientations of the horizontal and vertical sections are generally made. Contiguous with both the horizontal and vertical sections are "bean-bag" padding sections, the cover of which is airtight.
A patient is seated on the form. An acceptable vertical orientation of the vertical portion is made, as is an acceptable horizontal orientation of the horizontal portion. A shaping of the cushions is undertaken to provide an acceptable force distribution along the portions of the seat contacting the patient. After this has been accomplished, air from the cushions is evacuated, thus forming a semi-rigid seat which matches an acceptable contour.
Next, a casting, such as a powdered gypsum plaster of paris casting, is made of the selected seat contour. After hardening, this casting is carefully boxed and shipped to a seat manufacturer.
A seat manufacturer, upon receipt of the casting, undertakes a series of measurements of various cross-sections thereof. This cross-sectional information is used by a machinist to hand-cut sheet stock to the approximate dimensions of a measured cross-section. Individual cut portions of sheet stock are trimmed and refined until they closely approximate a cross-sectional portion of the form from which the casting was made.
After this time, a second cross-sectional measurement is taken at a distance from the preceding one, which distance is dictated by the thickness of the sheet stock being used for fabrication. This process is repeated for the entire casting.
Upon completion of cutting of all sheet stock portions, they are secured to one another to form a seat cushion resembling, as closely as possible, the casting. Given that discrete sheet portions have been used to fabricate the seat, rough corners between the various sections must be smoothed to acceptable tolerances.
It is apparent that the above-noted procedure, while often yielding acceptable seating, is a laborious, time consuming, and accordingly, expensive. Delays are experienced which are resultant from time necessary to prepare the casting, time necessary to ship the casting to a manufacturing location, and time necessary to manually measure, cut, refine, trim, and assemble, the series of sheet stock from which the support is manufactured. In addition, castings are susceptible to breakage, and introduce added error potential into the manufacturing process. Presently, fabrication of seating with the above procedure requires investment of several thousands of dollars, and several months in time.
In addition to the time and expense associated with the above-described manufacturing process, a patient must accept problems associated with improper seating for extended periods while he or she awaits receipt of the completed prescription seat. Such delays may find a patient with physiological characteristics altered due to improper seating during the wait.
The present invention contemplates a new and improved system for achieving a personalized support system which overcomes all of the above-referred problems, and others, and provides a system for arriving at a prescription support efficiently, economically, and with improved accuracy.